Semiconductor die or chips are encapsulated in a semiconductor package for protection from damage by external stresses and to provide a system for carrying electrical signals to and from the chips. Many different types of semiconductor packages exist, including dual-in-line packages, pin grid array packages, tape-automated bonding (TAB) packages, multi-chip modules (MCMs), and power packages. One type of power package is a high power package that is used for a high power semiconductor device and that is capable of dissipating greater than ten watts of power.
Typically, these power packages use a relatively high resistivity die attach materials that have a high lead content, a large thickness, and a low thermal conductivity of approximately twenty to thirty watts per meter Kelvin (w/m-K). Each of these characteristics contribute to heat transfer problems during device operation. Radio frequency and other high frequency power packages also typically have an air cavity enclosed by ceramic components, which are expensive. Lower cost high frequency encapsulated power packages are typically limited to a single semiconductor chip per package, which requires: (1) matching components to be located on the same chip as the high power semiconductor device, which can result in lossy devices with lower electrical performance; or (2) matching components and/or other components to be located on one or more different chips in different packages and requires a larger footprint or a larger amount of space in the final product for multiple packages.
Accordingly, a need exists for a low cost package for a high power semiconductor device that has improved thermal conductivity for improved reliability, that is less expensive than air cavity packages, that can be used to package multiple semiconductor chips in a single package, and that is compatible with high frequency applications above approximately three hundred MegaHertz (MHz).
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly connected in an electrical, mechanical, chemical, or other manner.